This invention relates to printing systems, and more particularly to a printing system in which some characters or symbols are printed with additional emphasis.
In printing sentences, sometimes it is necessary to print particular characters, phrases or symbols with additional emphasis. In order to meet this requirement, in an impact type printer, such characters, phrases or symbols are printed plural times so that they become higher in density.
However, in most non-impact type printers, even if the same position is printed plural times as described above, the density is not increased as expected; that is, it is practically difficult to increase the visual effect of the printed characters, etc. For instance, in a printer employing a thermal transfer system, a recording medium coated with thermally soluble or thermally sublimating ink is used in a manner such that the ink at the portion where printing is effected is heated so as to be transferred onto the recording sheet. Under normal recording conditions, the ink thus heated is substantially completely transferred onto the recording sheet. Accordingly, even if the same part of the recording medium is again heated, the amount of transferred ink is scarcely increased. In other words, the same position is printed plural times as described above, but the density of the position is not increased to the extent that it is clearly distinguishable from that of other printed positions. Furthermore, it should be noted that in the thermal transfer type printer, the recording medium is placed in surface contact with the recording sheet, so that the ink is transferred from the former to the latter. Therefore, it is impossible to employ a method in which, after the recording medium used for recording is peeled off the recording sheet, an unused portion of the recording medium is brought into contact with the recording sheet, to increase the amount of ink transferred.